package demo2;

//
//import java.util.Scanner;
//
//public class Main {
//    public static void main(String[] args) {
//        Scanner scanner = new Scanner(System.in);
//        while (scanner.hasNext()) {
//            String str = scanner.next();
//            String sub = scanner.next();
//            //System.out.println(str.indexOf(sub));
//            int len = sub.length();
//            int count = 0;
//            int index = -len;
//            while(true) {
//                index = str.indexOf(sub,index+len);
//                if(index == -1) break;
//                count ++;
//            }
//            System.out.println(count);
//        }
//    }
//}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        long[] fab = new long[100];
        fab[1] = fab[2] = 1;
        for(int i = 3; i<100; i++) {
            fab[i]= fab[i-1] + fab[i-2];
        }
        while(scanner.hasNextInt()) {
            int from = scanner.nextInt();
            int to = scanner.nextInt();
            long sum = 0;
            for(int i = from; i<=to; i++) {
                sum += fab[i];
            }
            System.out.println(sum);
        }
    }
}
